The invention concerns a roller for application of a medium, in particular a paint roller, with a support arm bearing the roller axle on which at least one application roller is borne for rotation.
Rollers are used in various areas for application of a coating medium. The application of paint is discussed herein by way of example although the invention could be utilized with other coating media in a similar manner.
In order to apply paint to a flat surface, conventional paint rollers comprise a support arm made from metal or plastic having a handle at the lower end thereof. The support arm is bent over at its upper end so that a substantially straight roller axle is formed extending perpendicularly with respect to the handle, on which one or a plurality of paint application rollers can be placed. In order to paint a surface, e.g. a wall, the paint roller and the paint application rollers are dipped into the paint and then passed over the surface to be painted, wherein the paint application rollers roll along the surface to thereby dispense paint. In this fashion, a flat surface can be rapidly and effectively painted. However, the painting of curved surfaces, e.g. pipes or corrugated plates is very tedious, since only very short sections of the straight paint application rollers seat on the curved surface.
Paint rollers have been developed for painting curved surfaces, the roller axles of which are curved in a particular predetermined direction. A plurality of short paint application rollers are placed onto the curved roller axle, disposed at angled orientations with respect to each other so that they seat on differing sections of the curved surface to be painted. This has, however, the disadvantage that the fixed predetermined curvature of the roller axle with the paint rollers can only be used to paint curved surfaces which have the same or at least similar curvature as the roller axle. In practice it has turned out that in order to paint pipes having a diameter between 50 mm to in excess of 1000 mm, a plurality of different paint rollers must be available. This creates storage problems and is also expensive. Should a deviation obtain between the radius of the curved surface to be painted and the radius of curvature of the roller axle, the paint application rollers only seat on the surface at sections or even at points which leads to increased local loads on the paint application roller and to associated irregular paint application. In addition, the orientation of the paint application roller relative to the handle is fixed so that it is difficult to use the roller under certain working conditions.
Also known in the art is the spreading-out of the support arm in a forked fashion at its forward end facing away from the handle and the spanning of a flexible spring between the free ends of the forked portion, upon which a plurality of paint application rollers are borne. In order to introduce paint onto a curved surface, the user presses the paint application rollers against the surface to be painted, wherein the curvature of the spring adjusts to the curvature of the surface to be painted. It has, however, turned out that the pressure which is to be introduced by the user to bring the roller into the desired curved shape, leads to an irregular and in particular a substantially point-like loading of the central paint application roller, as a result of which the paint contained in the paint application rollers is pushed out in a sideward direction making the paint application uneven and furthermore possibly leading to the running of paint. The unevenness of the paint application is further increased by the fact that the spring is unstable and does not have a defined curvature. Since the paint application rollers and the spring are captured by the forked portions of the support arm on both sides, it is not possible to introduce paint into corners. In addition, painting of pipes already mounted to a wall is practically impossible on the back side facing the wall. Additionally disadvantageously the orientation of the paint application roller relative to the handle cannot be changed which makes handling of the roller more difficult.
It is the underlying purpose of the invention to create a roller for application of a medium, in particular a paint roller, with which a coating medium can be applied evenly and easily to both a flat as well as to a curved surface.
This purpose is achieved in accordance with the invention with a roller of the above mentioned kind in that the curvature of the roller axle can be changed by an adjustment device and the adjusted curved orientation can be fixed in each case.
The adjustability of the curvature of the roller axis facilitates adjustment of the roller to the curvature of the surface to be covered so that both pipes having small diameters as well as pipes having large diameters can be advantageously painted using only one paint roller without having to have a plurality of paint rollers be available. Fixing of the roller axle by the user to an adjusted curved orientation can lead to a more even application of the paint, since the curvature of the roller axle is not dependent upon the pressure introduced by the user. Furthermore, the roller axle can be straight, so that the paint roller can also be used to paint flat surfaces in a conventional fashion.
The curvature of the roller axle is preferentially effected by applying a flexural moment of continuously changeable magnitude onto the roller axle using the adjustment device. The flexural moment can e.g. be effected by exerting an eccentric pressure and/or tension force on the roller axle, the eccentricity leading to a curving of the roller axle. So long as the forces generating the flexural moment are active, the roller axle is fixed in its curved position. With predetermined eccentricity for the tensioning forces, the continuous variation thereof facilitates an associated continuous adjustment of the curvature.
A preferred embodiment of the invention provides that the roller axle consists essentially of at least two parallel adjacently extending axle members of which at least one has a length which can be changed or adjusted relative to the other axle member using the adjustment device. The axle members are thereby connected to each other at certain locations and the curvature of the roller axle can be changed through a shorting or a lengthening of at least one of the axle members. When the adjustment device shortens the one axle member, this shortening results in a pressure force on the other axle member via an engagement section between the two axle members to effect curvature of the entire roller axle. If the length of the other non-adjustable axle member held by the support arm and the length of the adjustable axle member are equal, a linear orientation of the roller axle results. The adjusting device is preferentially a tension screw in threaded engagement with the adjustable axle member so that a rotation of the tension screw draws-in the adjustable axle member to thereby lead to a reduction in its instantaneous length, to curve the roller axle. Use of a tension screw also has the advantage that a continuous adjustment of the curvature can be effected in a simple manner.
Alternatively, it is also possible to subject the roller axle to an eccentric pressure and/or tensile force which e.g. can be effected by means of internal tension or pressure bands. The eccentricity leads to a curvature of the roller axle in dependence on the magnitude of the applied pressure or tensile force.
The axle components which can be adjusted relative to each other are preferentially connected to each other at their free ends facing away from the support arm and the tension screw and can slide freely in the intermediate region during adjustment. When the length of the adjustable axle member is shortened by rotating the tension screw, a pressure load acts on the stationary axle member at the opposite free end of the roller axis via engagement therewith, wherein there is no force transfer between these components in the intermediate portions of the axle members so that an even, continuous curvature of the roller axle can be achieved along its entire length.
The introduction of a flexural moment or an eccentric tensioning force can effect a curvature of the roller axle in a single plane. In order to increase the range of applicability of the paint roller, an improvement in the invention provides that the roller axle can be brought into various pivot locations relative to the support arm, as a result of which the plane of curvature of the roller axle can be adjusted relative to the support arm and thereby relative to the handle in order to optimally adjust the support arm to the instantaneous working conditions. Although it is possible to provide a continuous adjustment of the roller axle relative to the support arm, it has, in practice, turned out to be preferable when the roller axle can be latched into defined pivot positions preferentially in intervals of 30xc2x0 or 45xc2x0.
It can be useful to have roller axles of differing axial lengths in dependence on the size of the curved surface to be covered. This can be achieved in accordance with the invention when the roller axle is held on the support arm in a detachable fashion so that it can be rapidly exchanged if necessary. This has the additional associated advantage that only one single support arm, with handle, must be provided for various roller axles upon which the desired roller axle can be mounted in each case.
A preferred embodiment of the invention provides that the application roller or rollers are held on the roller axle in an exchangeable fashion. A plurality of coaxially disposed partial rollers can thereby be provided. In this fashion paint application rollers made from differing materials and/or having differing surface shapes or structures can be utilized together or in sequence on a common paint roller. The paint application rollers are placed onto the roller axle at the free end thereof and preferentially held at this location via frictional forces. The paint application rollers are prevented from slipping off the roller axle by means of a stop member, e.g. a stop nut, disposed on an end of the roller axle. In order to remove the paint application rollers, the user must only detach the stop member from the roller axle and subsequently axially remove the paint application rollers therefrom.
The paint application rollers should be made from an elastic, flexible material in order to be able to precisely follow the curvature of the roller axle. In particular, longer paint application rollers thereby have only a small amount of resistance which must be overcome to curve the roller axle. This simplifies adjustment.
In order to be able to recycle the entire roller it is, in particular, completely made from plastic, wherein a further improvement therein can provide for the use of only one type of plastic.
Additional details and features of the invention can be seen in the following description of an embodiment with reference to the drawing.